Proportioning apparatus and method for mixing and feeding liquid resin impregnant with setting agent through single orifice discharge



J y 1965 A. LIGGENSTORFER ETAL 3,193,202

PROPORTIONING APPARATUS AND METHOD FOR MIXING AND FEEDING LIQUID RESIN IMPREGNANT WITH SETTING AGENT THROUGH SINGLE ORIFICE DISCHARGE Filed Nov. 6, 1962 F/G.l

"i INVENTORS ARNOLD LIGGENSTORFER BRUNO BEELER BY Q ATTORNEY United States Patent PROPORTIONING APPARATUS AND METHGD FOR MKXING AND FEEDHNG LIQUID RESIN IN!- PREGNANT WITH SETTING AGENT THRQUGH SINGLE ORIFICE DISCHARGE Arnold Liggenstorfer, Stockenerstrasse 4, Winterthur-Seen, Switzerland, and Bruno Beeler, Brnlilhergstrasse 1'7, Winterthur, Switzerland Filed Nov. 6, 1962, Ser. No. 236,476 2 Claims. (Cl. 23142) The invention relates to an apparatus and method for mixing and feeding a liquid impregnant mixture consisting of a resin and a resin setting agent to a point of single orifice discharge, especially suitable for impregnating the windings in the slots of armatures and stators. The invention also relates to apparatus for performing the proposed method.

In order to impregnate armature and stator windings without the application of elevated temperatures within the shortest possible time it is the practice to add a setting agent to the resin. Naturally the setting agent cannot be added to the resin until immediately before the resin is to be used, as otherwise the premature addition of the setting agent causes the liquid resin impregnant to set too soon and the liquid quickly loses its fiowability before reaching the more remote parts which are to be impregnated therewith. Moreover, if at any time during the mixing and feeding operation the continuous discharge of the mixture is interrupted, the plug remaining in the nozzle must be substantially completely removed before it hardens to block the nozzle.

The apparatus proposed by the invention consists of a specially constructed device for feeding the two components, e.g., liquid resin and liquid setting agent, of the mixture each separately into its own metering mechanism comprising a cylinder and a piston reciprocable by a lever arm of variable length, this metering mechanism predetermining the given or overall quantity of both components which are separately pumped from the re spective sources in given proportions into the mixer chamber above the nozzle head to be mixed there-in and then immediately discharged through the nozzle. The apparatus is provided with special means for withdrawing the plug of mixture left in the nozzle, in the event of an interruption of the discharging process, this means embodying an evacuation mechanism in the mixing head operative to prevent solidification of the plug inside the nozzle when the ordinarily continuous impregnation operation is temporarily stopped.

The novel apparatus for performing the liquid proportioning and liquid mixing method comprises two separate cylinders each cylinder containing a piston and piston rod, one connected with a storage vessel for the resin and the other with a storage vessel for the setting agent and each separately communicating through its associated tubing with a mixer chamber in combination with a single orifice discharge nozzle, said piston rods being each operatively attached to a lever arm at points located at an adjustable and preselectable distance from the fulcrum of this lever arm whereby both the separate and overall quantities of both components for mixing as well as the proportions which are delivered are controlled. The lever arm is so articulated to the piston rod of the thus described doubleacting driving piston that the resulting proportioning mechanism permits constant flow to the mixing chamber.

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The mixing chamber contains a rotating mixing blade operatively connected to a vacuum pump which provides the plug withdrawal operation above described.

The apparatus will now be described in greater detail by reference to the drawings which show a particularly preferred embodiment of the present apparatus for performing the mixing operation.

In the drawings:

FIG. 1 is a schematic representation of the metering and mixing means;

FIG. 2 is the mixing nozzle shown in section.

The principle of operation of the apparatus may be seen in connection with FIG. 1 particularly. From a storage vessel 1a liquid resin can be drawn into a cylinder 3a by means of a piston 4a. The piston rod 5a is pivotally linked to a lever arm 6 which is fulcrumed at 7 and is reciprocated by a piston rod 8. A feed pipe 9a is provided which connects cylinder 3a with the mixer head 10.

The setting agent in liquid form is drawn from a sep arate source, e.g. storage vessel 1b through a pipe 212 into a second cylinder 3b containing a piston 4b with a piston rod 5b which is likewise pivotably linked to the said lever arm 6, and there is provided a second feed pipe 91) connecting the second cylinder to the mixer head iii.

The mixer head comprises a cylindrical body 11 provided with a connection 12 for feed pipe 9a which supplies the liquid resin and with a connection 13 for feed pipe 9b which supplies the liquid setting agent. A further connection 14 leads to a vacuum pump 15. The mixing head in its interior contains a mixing blade in which is driven by a motor 17 and which is shaped to sweep the entire inside cross section of the cylinder and thus to provide an intense mixing action and to keep the mixture constantly in motion.

The proportion of resin and setting agent in the mixture is a matter of great importance and may vary according to the nature of the materials used. The desired proportion in the mixture may be varied by changing the point at attachment of the piston rods 5a and 5b to lever arm 6. A change of the fulcrum of the lever arm likewise causes the proportion of the components in the mixture, the mixture ratio M, to be changed. This ratio is determined by M=x/y assuming the cross sect-ion of the pistons remains the same.

The total quantity delivered is determined by the angle of deflection oz of the lever arm 6. The piston which reciprocates the lever arm by means of its piston rod 8 must be double-acting in order to draw the liquid resin as well as the liquid setting agent from their respective containers during the one stroke and thereafter to force resin and setting agent into the mixing head during the ensuing stroke. It will be understood that the several pipe lines and connections schematically shown in FIG. 1 must incorporate the necessary conventional valve means in order to carry out the double-acting pumping operation.

Resin and setting agent enter the upper part of the cylindrical body 11 each in liquid form through separate pipes, as shown in FIGS. 1 and 2, and it is on their way to the discharge nozzle 18 that they are first mixed, the provision of the revolving blade 16, as shown in FIG. 2, intensifying the mixing effect. The mixture must not be permitted to remain inside the mixing head 10 for any substantial length of time, since otherwise, the resin would harden and solidify therein to completely block the mixing chamber.

(not shown). with electric heating means to permit the liquid phase to By the depression of the pistons 4a and 411 by lever arm 6, metered quantities in the correct proportions of resin and hardening agent for forming the desired end use mixture are forced out of the cylinders 3a and 3b through pipes 9a and 9b and into the mixer. The introduction of the components into the mixer ceases as soon as the lever arm 6 reaches dead center. The components are mixed under agitation by rotating blade 16, and the mixture passes while being stirred in the form of a viscous liquid mass into the nozzle from which the viscous liquid mixture is then discharged. Since the mixer head has been fed with an exactly metered quantity, the entire contents should flow out to correspond with the said metered quantity. Nevertheless a small residue might remain inside the nozzle where it could solidify and cause a blockage. This is prevented by generating a vacuum inside the mixer head through connection 14, from a vacuum pump (not shown), said vacuum pressure sucking back the residual plug so that the nozzle is kept free.

If desired, the nozzle may be fitted with a slide valve Also the mixer head maybe provided be obtained with normally solid resins capable of setting with the addition of hardening agents.

Having thus disclosed the invention, what is claimed is:

1. Apparatus for mixing and feeding a liquid impregnant mixture, consisting of a resin in liquid form and a setting agent in liquid form, to a common point of single orifice discharge; a metering mechanism for measuring the delivery of the liquid resin, a separate metering mechanism for measuring the delivery of the liquid setting agent, each of the first and second metering mechanisms consisting of a cylinder containing a piston, a piston rod an open discharging nozzle located at the bottom of said mixer chamber for discharging the impregnant mixture; said open nozzle being formed as a conical section at the base, and the mixer blade having a bottom section which sweeps the cross-section of said conical base to force the resin mixture out of said nozzle by the rotating action of said blade.

2. Apparatus as claimed in claim 1 wherein said mixer chamber is provided with evacuation mechanism in the mixer head to prevent solidification of the resin and setting and a storage vessel having an outlet; a mixer chamber connected by means of associated tubing to the outlet of each of said storage vessels; a common lever arm fulcrumed at one end thereof to which is attached the free end of the piston rod for the liquid resin storage vessel and the free end of the piston rod for liquid setting agent storage tank; a double-action driving piston fitted with a cylinder and a driving piston rod, said driving piston rod being connected to said lever arm at a point between the attachment of the liquid resin storage vessel piston rod and the liquid setting agent storage vessel piston rod, these last two points of attachment being adjustably located at agent .as a plug inside the nozzle when flow is stopped.

References Cited by the Examiner UNITED STATES PATENTS 2,747,932 5/56 Volk 2391 2,764,565 9/56 Hoppe et a1 239--'142 2,946,488 7/60 Kraft 222334 2,958,471 11/60 Zippel 2394l4 2,993,648 7/61 Blackwell 2391 3,008,808 ll/6'1 Hodges 239407 3,035,775 5/62 Edwards et a1 239142 3,038,750 6/62 Nielsen 2394O7 3,055,596 9/62 Pope 239407 3,057,273 10/62 Wilson 239-142 3,071,293 l/ 63 Lewis-Smith et al 222334 3,079,090 2/63 Decker 239142 3,083,913 4/63 Coffman et al 239l4 FOREIGN PATENTS 1,015,726 9/57 Germany.

EVERETT W'. KIRBY, Primary Examiner. EDWARD J. MICHAEL, LOUIS DEMBO, Examiners. 

